The Test Environments section of the test plan includes two tabs:
Use the Platform Coverage tab to create a non-binding list of platforms that you hope to cover. This is where you specify the required operating systems, browsers, supported hardware platforms, CPU-types, and so on. Typically, you might use Platform Coverage as a high-level planning tool. For example, your Platform Coverage list might appear as follows:
Use the Test Environments tab to list the actual combinations of environmental attributes that are available for testing on test lab machines. The Test Environments list might appear as follows:
It is not a requirement that you specify platform coverage or test environments in a test plan. Nor is a test plan required for test execution. However, if you specify test environments in your test plan, the test execution wizard will utilize those attributes when creating the test execution records for the test cases. If you choose not to define test environments in your test plan, or you do not have a test plan, a complete list of attributes will be available during test execution.